Physicians make widespread use of catheters today in medical procedures to gain access into interior regions of the body. In its important that the physician can control carefully and precisely the movement of the catheter within the body.
The need for careful and precise control over the catheter is especially critical during procedures that ablate tissue within the heart. These procedures, called electrophysiological therapy, are becoming more widespread for treating cardiac rhythm disturbances.
During these procedures, a physician steers a catheter through a main vein or artery (typically the femoral artery) into the interior region of the heart that is to be treated. The physician then further manipulates a steering mechanism to place the electrode carried on the tip of the catheter into direct contact with the tissue that is to be ablated. The physician directs radio frequency energy into the electrode tip to ablate the tissue and form a lesion.
Cardiac ablation especially requires the ability to precisely bend and shape the tip end of the catheter to position the ablation electrode. Previous steering control mechanism have generally applied pulling and pushing forces on a pair of steering wires by winding and unwinding them around a rotatable cam wheel. Such mechanisms have a relatively short life due to metal fatigue occurring in the wires caused by repeated bending and straightening thereof.